The Mistress & the Conuslting Detective
by ShootingSparkles
Summary: What happens when one of the world's most notorious thieves meets the world's only consulting detective? The Mistress is a thief responsible for some of the greatest heists of the century. But when an anonymous person tries to slander her reputation she must form a partnership with an arrogant, sociopathic consulting detective. But hey takes a sociopath to know a sociopath. SH/OC
1. Chapter 1

**Author's Note:**

**Starting a Sherlock fanfic. Scared because of the complexity behind the characters and hoping my original character can match up!**

**I do not own Sherlock. **

**Enjoy!**

* * *

1.

Paris is a beautiful city. No matter how cliché it was, Olivia Tate couldn't help but think: Paris was even more beautiful at night. It was the City of Lights, not so much the city of romance, in her not so humble opinion. Well, it could be. She just hadn't seen any romance, but it was probably because she didn't care enough to look. Stranger romance, it was weird-it was practically alien to Olivia. Sure she had been in her share of romances, but they never involved that much PDA or touching in general.

But she was only twenty six, she still had a while to experience touching from the opposite sex.

No, what Olivia Tate was doing in Paris was more than sight-seeing and people stalking. She was here on a...vacation as only she would call it. Olivia smirked as she thought of her 'hunting ground'. The great country of England. Home of so many lovely places to go, things to see, people to...well people can be used for all kinds of things. And so can museums. But she had overstepped many boundaries back in the great land of England, which was why she was towards the end of her two year hiatus in Paris. Getting away from the busybodies of the English government and police force. Really, they both were quite bothersome.

She didn't have to stay in England. But it was quaint. She was nomadic but for some reason she always came back to England. After China, after Singapore, after America. Always England.

...Two Years Ago...

Olivia Tate walked into a building, a very fancy building with old architectural designs, yet a very modern and high tech on the inside. Ah the government, Olivia thought with a smirk, they thought they were so clever trying with their underlying metaphors of the combination of the old culture and the new.

Agents and government officials stared at her as she passed. She rolled back her shoulders and kept her proud smirk fixated on her face, her mask of cool, calm composure. Not a hard mask to keep on. Not a facade just an exaggeration of the truth. With each step she took, the click of her heels on the smooth marble floor sounded throughout the building mixing with the sounds of softer, less confident footsteps and typing and whispered mutterings from the lackeys of the government.

She stopped in front of a man, a man exuding power. A man of power and he knew it. Foolish man. If he had so much power, how come he couldn't stop her?

"Miss Alexandria Langlis," the man of power greeted.

"You called, but I am Teresa Montgomery, I know no one by the name of Langlis," Olivia said, barely keeping the smugness out of her Scottish brogue. Congratulations to the British government, they had made it farther than the other governments. Good for them, too bad they wouldn't get farther than her Langlis front.

"Enough games, Miss Langlis," the man snapped, "We know of your true identity now, Teresa was just a ploy.

"Yes, very good," Olivia smirked, "Now why am I called here?"

"We have reason to believe that you are in association with a notorious thief that goes by the name of the Mistress," the man said, "Is this true?"

"Do you have anything to prove of this so called association?" Olivia asked.

"No-," the man started.

"Then why are you wasting my time?" Olivia asked, "I am not in association with this burglar. Burglary is below me, do you know how much my family makes a year? Why would I need to associate myself with those kind of people?"

Foolish man. He thinks he understands what he is trying to solve.

"Well," the man said flustered, "do you have any idea of the whereabouts of the Jade Sphere?"

The Jade Sphere was a pricy jewel that only the queen and one other 'mystery' person in the government know about its whereabouts. This Sphere was among the top ten most valuable gems in the world.

"The Jade Sphere?" Olivia asked slowly, "I'm afraid not, however, I have read it has been stolen."

"Yes, we are getting closer and closer to the thief," the man said, "Our ties led up to the Langlis family, there was a lot of financial activity between the Mistress' thievery and the family. We went through their banking records and found the offshore account."

"What are you telling me this?" Olivia asked.

"Well your family is very powerful, Miss Langlis, we believe that the criminal in question will try to sell the jewel to the highest bidder, to get rid of it," the man said.

"But then wouldn't they need to give it back to the government," Olivia said with an eye roll, "Who would buy the jewel? You obviously know nothing about jewel thievery. They cannot sell a highly profiled piece, jewelry or art. In this case, the thief will most likely cut the jewel down and sell the jade bits to local stores or makers or just buyers in general. If you're going to call me here, at least get a decent understanding of what you are accusing me of."

The man just stared at her. Olivia fought the urge the chuckle deviously. The Langlis family was such a good cover story. They owed her a favor, so she posed as Alexandria, the daughter no one knew about. The real Alexandria was dead, but now Olivia had her information, her security codes and her life in her hand. It was only her second name, she kept her first defenses strong as well as her last. Masquerading as Alexandria Langlis was simple and extremely believable. The Langlis family was notoriously secretive. Even the government couldn't crack them because the government placed their trust too heavily on some people. And the Langlis's had money. Lots of it. And in the past they had made large, helpful donations to the government in times of crisis. The British government couldn't touch them.

"By the way, how did you discover that Teresa Montgomery was truly Alexandria Langlis?" Olivia asked. She always loved it when the government gave away secrets to those who were 'trusted' it gave her a chance to strengthen her ties and other identities.

She had grown sloppy and now her first identity was discovered. She had been living as Teresa Montgomery since she was one. Olivia Tate had been homeschooled all her life, her parents had died when she was one and a woman had found her, naming her Teresa Montgomery. She had discovered her true identity of Olivia Tate, but for all everyone knew, Olivia Tate never existed.

She used these identities, her numerous connections and her overall ability to keep a secret to prevent the government from ever having the hope of touching her. Or discovering her solo operation. It was also a statement. She didn't need the different identities. But it was fun making the government seem foolish and unknowing. It was all a game to her. A fun game that no one had the hope of winning. They would always lose and she would always win. And Olivia Tate loved to win.

"It was simple, Teresa Montgomery had made two visits to the Langlis manor of recent and once we traced their money deposits to a small Swedish bank on the coast of the country which were being taken out by a Teresa Montgomery," the man said.

Olivia raised an eyebrow. Not bad for the government, no bad at all. It must have taken them years to figure out the small Swedish bank the Langlis' were depositing money to. The Langlis' started owing her when she turned twenty, six years ago, but she had started her operations when she was eighteen and she was extremely active since then.

Eight years of extremely active and obvious action. Honestly, she had been leaving her signature at every operative she worked in. No hints, just a signature-a simple piece of white paper with the Mistress signed in loopy cursive, so different than her own angular font. It was obvious that she had been circling the country, the world, but had never been apprehended. The government was bound to discover the back door of her first identity. But they'd never connect her to the Mistress. There was no evidence, just a tie to the Langlis family.

It was lucky that the lady who found the one year old Olivia Tate was an old village woman in a small farm in Scotland, never told anyone about finding Olivia and the knowledge that Olivia was not truly the daughter of a village woman died when woman died.

"Well, you know my family," Olivia said with a fake smile, "They're full of secrets."

"Secrets the government would like to know, for the safety of the people living in it," the man said.

"Well, would you look at the time," Olivia said straightening her already straight black pencil skirt before smoothing her straight black hair, "I must be going. It was lovely meeting you...?"

"Mycroft," the man said taking her hand, "Mycroft Holmes."

...Back in the Present...

Olivia found herself staring at the Mona Lisa in the Louvre. She stared at that mysterious painting in that climate controlled environment, encased in bulletproof glass. She stared into the unblinking eyes of the woman and the coy smirk of Mona Lisa. What was her story? What hid behind those eyes and that self assured little smile, or smirk as it appeared to Olivia whenever she visited the museum.

Olivia came to the museum many times. She was somewhat of an expert on art museums and art in general. She had an Art History major that was hidden behind a more prominent Mathematics major.

She had so many layers. She felt so similar to the Mona Lisa. So many mysteries that no one could figure out, but everyone tried. Yet no one had came close. So protected, yet she managed to get stolen and vandalized once or twice but otherwise it was unheard of.

She remembered when the society of underground thieves in Britain held a competition to steal the painting. Olivia

smirked. She had the painting in twenty four hours after the competition started leaving a piece of paper reading 'the Mistress' in the place of the painting and had kept it for twenty four hours. She was nineteen and she had only been working for one years. Her experience had worked to her advantage, she didn't over think the situation. Olivia watched the detective investigating her heist. He had been so dedicated but so annoying. She had planted the painting in his apartment building in Paris with her signature. That became her touch.

That heist had made the Mistress known. And her reputation became known amongst all the thieves in the world, all the governments and the people who had read about the heists the government kept under wraps. She had stolen hundreds of paintings from numerous museums, as well as a valuable jewel or statue here and there.

Her eyes flittered from the painting to the security guard that was staring at her intently. Probably waiting for her to whip out a camera and take some illegal photos. She stared back at him and raised her chin up daring him to question her. Olivia ran a hand down her, now natural caramel colored curls as she sauntered out of the museum.

She heard footsteps behind her and she ignored it, waiting for the person tailing her to follow. She could hide, she was pretty good at hiding, but why bother?

"Hey, you," a gruff male voice said.

Olivia stopped and turned around, "I have a name." And she was curious to know which one was going to be used.

"I've been informed that you are Miss Alexandria Langlis," the man said, "The British government sent me here to find you. You are not an easy woman to find, Miss."

"That's the purpose," Olivia answered, "Now what does the government want from me."

The man stood in front of her two paces exactly and pulled out a gun. Olivia rushed him the moment his hand reached out of his pocket. She grabbed his hand and twisted it, crushing it beneath her rather delicate looking hands. Foolish man, was this a test? She wondered. The gun fell to the floor and Olivia picked it up.

"Does the government want me dead?" Olivia asked, "Well, this is a first."

"No," the security guard said standing up from where he fell and massaging his hand. It wasn't broken, Olivia wasn't strong enough to break it, but it would be sore and bruised for a while. "It was just protocol. I was supposed to hold the gun up and ask for identification."

"You could have done that without the gun," Olivia said now pointing it at him. She reached into her small purse with a free hand. The guard stared at her picture.

The guard nodded, or rather he probably wasn't a guard, more likely a government agent.

"Well, I guess my vacation is over," Olivia muttered.

...

Olivia was told by that Mycroft Holmes bloke that she met with two years ago some extremely interesting information. He met her with a private governmental plane going back to England.

He showed her, via her tablet, the body of a man, completely white, but no discernable wound marks. Olivia figured that it was from some kind of needle mark, or poison being injected into his body. Lo and behold it was a needle of air being pushed into an important nerve in the neck doing some kind of medical mumbo jumbo. She zoned out when he started going medical examiner on her. She didn't understand that aspect of crime.

"His body had been labeled with a piece of paper labeled 'the Master'," he said, "Now the Mistress had been missing in action in England for a while. Right after we had you suspected. Are you sure you are not in association with her?"

"Can you prove any association yet?" Olivia asked.

"No," Mycroft had said begrudgingly. Olivia could tell he didn't like saying no and he liked to have complete control over the situation.

"Then why am I here?" Olivia asked.

"Because all our leads of the Mistress go every which way," Mycroft said.

"Do you still suspect me?" Olivia had asked again.

"No, you are no longer a suspect," Mycroft had informed her, "The government cannot find a solid link to you and the Mistress and your family made sure to keep it that way."

"Then you won't find a link," Olivia had said with a smug smirk, "No one will ever find out anything about the Mistress. The American government could not, the Chinese government could not, I don't think the British government can either."

"However," Mycroft had said with a stern look in her direction, "while the government still thinks of you as Alexandria Langlis and since you have that family so wrapped around your finger it cannot disprove it, I have digressed. I do not believe you to be the young Miss Langlis."

"Oh," Olivia said raising an eyebrow, "And what power do you have that is greater than that of the government?"

"The power of deduction," Mycroft said, "And using that power, I have deduced that you share no knowable link with the Langlis family, your features are not similar at all."

"Then who am I?" Olivia asked, "What is my true identity?"

Mycroft Holmes stared at her. The government didn't know. He didn't know.

"Then you cannot prove it, I am Alexandria Langlis," Olivia said with a shake of her head, "Your deduction has not concrete back up. It is what it is, a deduction-mere speculation, not solid proof. Circumstance not evidence. Test my DNA, it will come up as Alexandria Langlis but you've already done this, Mister Holmes, I can tell. That's proof enough."

"But it is enough to make me continue to search, I received this deduction under a trusted source," Mycroft said, "And I have searched and I have reason to believe that you are the Mistress."

"Well you cannot PROVE that," Olivia said, "This still does not explain why you brought some man to remove me from my vacation in Paris."

"Someone going by the name of the Master has been killing people, both rich and poor," Mycroft had said, "The government thinks that this Master is an acquaintance of the Mistress."

"The Mistress works alone and does not kill," Olivia said easily.

Inside her brain was working over time. How could anyone think that a murderer was working with a thief? Especially one as renowned and professional as the Mistress? Killing in thievery was the lowest of the low in that craft. The craft of thievery was sacred, it was an art of sneaking and not being caught. Murder was like cheating, like spitting upon the name of the craft itself.

"Yes, but those people that had been killed, all their belongings went with their life," Mycroft said.

"And the government thinks that is why the Mistress is working with this Master," Olivia said, "Well the government is foolish. The Mistress does not kill. Murder is below her, below all professional thieves, leaving people alive and desperate is much more fun."

Mycroft Holmes stared at her.

"You know a lot about the Mistress," Mycroft Holmes said.

"Can you keep a secret?" Olivia fake whispered, "You're right. I am the Mistress. Tell anyone and it is my word against yours. I know you hold a great position in the government, you practically are the British government, but the Langlis' will pay any amount of money to keep me safe. They will disprove you, even if it means using a scapegoat, and you will be the fool."

Mycroft Holmes looked stunned.

"You forget who pays the government," Olivia said, "The Langlis' have so much information the government keeps from its people. You tell them about my identity and I send the order to bring England to her knees. Naturally, that would be poor for you and your affairs."

Mycroft stared at her.

"Do you think I had not thought about this?" Olivia asked rhetorically, "That I would not have a back-up plan? Every country I have ever stolen from I have so much dirt on them, I have knowledge of all conspiracies and proof about all of them. There are so many secrets each of the governments are keeping from their citizens and I know the great majority of them. I could destroy each government, cause their citizens to revolt."

"Why tell me this?" Mycroft whispered.

"To let you know exactly who you are dealing with and to find your priorities," Olivia said softly, smugly, "You are powerful but so am I. But the difference is my theories have proof, yours do not. So I'm telling you my identity, knowing that you would not turn me in after finding out who I'm capable. You are the heart of the government but I hold that heart in MY hands. You control the happenings of the government but right now I control YOU."

Mycroft sat back in shock.

"I know Mister Holmes that sending me into some odd years of prison is not worth destroying a government that you are so involved in and took years and years to establish," Olivia said leaning close to the shell shocked man.

"How do I know you're not bluffing," Mycroft Holmes countered leaning close to her in return.

"Mister Holmes, I don't think you want me to prove it," Olivia whispered fixing her eyes on the man sitting in front of her.

It was silent in the plane minus the muffled roar of the engine before Olivia broke out of their staring contest to recline back on her plane's seat with a smug look and crossed arms.

"And I do not associate myself with murderers," Olivia continued, "I want to do something to find this Master. He is soiling my reputation."


	2. Chapter 2

**Author's Note:**

**Next chapter! Thank you to all that favorited, followed and reviewed. Continue doing so!**

**I still don't own Sherlock. Damn.**

**Enjoy!**

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2.

Olivia walked onto the crime scene. She glanced at the people slowing down to look at the flashing lights, ambulances and caution tape around the crime scene.

"You are not authorized to be here," a man in forensic gear shouted at her.

The other man the forensic man was talking to looked at her. This one she recognized. Detective Inspector Lestrade, Mycroft had informed her that he was in charge of the investigation.

"Who are you?" the DI said.

"Teresa Montgomery," Olivia said taking out her identification, "I'm here from the government."

"Under what grounds?" the forensic man asked.

"Anderson, settle down," the DI said holding out a hand to this Anderson man, "She is supposed to be here. I got the call from my superiors."

Olivia stared at him, "Let's just say, I am a sort of expert in the Mistress and her previous heists. I am here to provide insight since you normally investigate murders, not heists, and it's been speculated that she had an involvement in "

She would be investigating on her own terms. She would look around the crime scene, survey the area, what had been stolen and then check her own connections. These people wouldn't figure it out. They were just regular detectives.

"Why are they sending you here? You haven't found the Mistress, if your such an expert you would have helped the White Collar track her down," a woman's voice said, "I suppose you slack off on your job, don't follow regulations and don't get anything done."

Olivia stared at the woman then the man in the forensic uniform. She smirked at her, "I'm not the only one. Is there not some kind of code that goes against relations between co-workers?"

The woman and Anderson looked confused.

"I saw the two of you in the alley by the crime scene," Olivia said raising an eye brow at the Detective Inspector, "I'll be going to survey the crime scene now."

"Bitch," the woman muttered.

"Not a bitch, just the bearer of truth," Olivia said turning around sharply, lifting her arms to the side of her dark red trench coated body before turning around again, somewhat dramatically.

She straightened her scarf as she entered the room where the man, Lester Herman, had been murdered by the Master. Olivia stopped when she realized she was not alone in the room.

The two man standing over the body, well one was standing over, the other was on all fours staring at the dead man's finger.

"I need the room cleared," Olivia said.

The man crouching stared at her then got up slowly. The man that had been standing walked over to her and held out a hand, "Dr. John Watson and-"

"Sherlock Holmes," the man by the body stated. Olivia looked at him, the complete opposite of his cohort, John Watson.

Sherlock Holmes, brother of Mycroft Holmes-her reason for being here. Apparently, consulting detective extraordinaire, able to tell you your entire life story with a single glance, impressive but Olivia never believed everything she read online and families tend to over-exaggerate. Sherlock Holmes was quite the looker with dark curls and blue green eyes. The man's cheekbones looked like they could cut diamonds, he was all angles and marble white skin. His counterpart John Watson was shorter, warmer looking with blondish hair. While Sherlock Holmes's eyes held a cold, calculating look, John Watson's held a sort of warmth, yet the lines in his face proved he had come from hardship and could be stern.

"Theresa Montgomery," Olivia said.

"Ah, Miss Montgomery, I see you met our consulting detective and his partner," the detective inspector said with a nod towards Sherlock, "We call him on to cases on occasion."

"Consulting detective," Olivia asked playing the dumb card.

"Yes, I come when they cannot hope to find the murderer," Sherlock stated coldly, "Your victim, Lester Herman was the CEO of TechNow. His wife is outside currently bawling her eyes out to one of your officers but while she seems to be consumed with sentiments for the dead man, he was having a year-long affair with one of his secretaries."

"Freak," the woman said.

"I see you have a penchant for muttering insults under your breath," Olivia stated coolly at the woman. She did not like being insulted and hadn't gotten over the fact the woman called her a bitch. "How can you be telling me I am rubbish at my job when you need to call a civilian to do yours for you?"

The woman looked shocked, "Why you little bitch."

"Donovan," the detective inspector warned.

"Sir, you heard her," Donovan protested.

"Yes and everything was true," Sherlock stated in a bored voice, "Except for when you said I was merely a civilian I am so much more than a civilian, I am the world's only consulting detective."

"Like I said," Olivia said staring at this Donovan, "I am just merely a bearer of truth."

The man, John Watson stared at her then shifted his gaze towards Sherlock Holmes who just looked at her with that vacant cold expression.

"Anyway," the DI said, "Do you think the woman he was having an affair with hired someone to kill him?"

"I have already thought about that," Sherlock said holding a note, "Shelby Norman, Lester Herman's secretary. John and I will go to her right after."

"Wait," Olivia said, "How did you know that he was having an affair? What is your proof?"

"This note with the woman's number on it, the fact he has napkins from a motel and a shirt in his room stained with pink lipstick," Sherlock stated at her dryly.

"She's his secretary, he needs her phone number, the napkin from the motel could have been where he and his wife went to do their thing and the lipstick could have been hers as well," Anderson said.

"God, Anderson, you are a complete and utter moron," Sherlock stated shaking his head and glaring at the man, "Why do you keep him around when he is clearly incompetent? If you had all that money would you go to the most run down motels in the city with your wife? Why not a better place, a suite in a hotel perhaps? But you can't take your mistress to a nice hotel where people know your name and can be tracked down from. And his wife doesn't wear that shade of lipstick. It doesn't go with her skin tone and she was wearing a nude shade outside, not a bright shade like the one on his shirt."

"Fascinating," Olivia murmured, "I understand how you come in handy with the police force. You are good with the preliminary speculation."

It's a good thing that the Mistress was a white collar problem not anything involving murder. But then again, this was all deduction, no concrete proof to send someone away. He'd get close but he wouldn't touch her. He reminded her so much of Mycroft. They were intelligent and they knew it. But they had faced many challengers and presumably won, making them cocky. But they hadn't met her yet.

"But whoever it was," Sherlock continued, "the victim knew them. There is no signs of breaking and entering or struggle. He is in regular clothes and he does not look prepared for guests. Lester Herman has a state of the art security system in his apartment so no one could break in."

Olivia stared at the security system Sherlock Holmes had pointed out. Thomas & Rollands Inc. Olivia smirked. Thomas & Rollands was a company that made security systems. Anthony Thomas and Clark Rollands were tech genius, graduated from top schools and known allies with the more skilled professional thieves in the world. Olivia was one of those thieves.

Anthony Thomas's father was a known thief, which was a good cover story for their company. The sob story he gave the public: "My father had broken into the homes of numerous people, he had taken their belongings without mercy. If they only had a better security system, they would have been better protected." It was brilliant. What the public wasn't allowed to see was that Anthony and his father held the tightest of bonds.

However, Anthony was clumsy, not stealthy like his father was so instead of going down his father's path, he spent his life trying to help the thief business in his father's name. His top 10 thieves knew about this. They paid them top dollar to know the information of their clients to break into the homes easily and without proof of entering.

So, Olivia thought, Anthony and Clark might know this Master. How deliciously simple.

"Did the other victims have this security system as well?" Olivia asked.

"Yes," the detective inspector said.

"Well," Olivia said, "I'll just need your notes on the items that went missing from the apartment and I'll be off to White Collar to find who stole the items."

"It was the Mistress," Donovan said with an eye roll.

"Don't be foolish," Olivia said, "The Mistress works alone. And has never had a history of allying herself with murderers. Of course someone such as you would pick the most obvious and blatantly wrong victim. Besides, the Mistress has not committed a heist in two years."

"You really are a bitch," Donovan said with a breathy laugh.

"Bearer of truth," Olivia said standing up straight and crossing her arms once again over her trench coat, "For example, here's some truth that others may misconstrued as bitchy: I am almost 100% certain inter-office affairs are strictly forbidden within the police force, as I stated before. However, you and that forensic man that questioned me, Anderson you called him Anderson? You two are in some kind of affair. And from the ring indentations under his glove, he's married. How scandalous."

Sherlock Holmes stared at her as if he had forgotten she was in the room. He narrowed his eyes at her, "What was your name again?"

"Theresa Montgomery," Olivia answered, "I'm here from White Collar."

"No," Sherlock said, "You're not from White Collar."

Olivia raised an eye brow at him. Mycroft had told her this was happen. And now she was excited to see the deducing skills of the world's only consulting detective on her own person. She wondered what he would get.

"Sherlock, don't," John said running a hand down his faced.

"You have just returned from a vacation of two months-most likely in Paris or another major city in France, you do not work for White Collar although you have history in crime, most likely a family history -someone in your family was most likely a cop," Sherlock said, "however, your parents are dead, have been for a long time and you live alone."

Olivia raised an eyebrow at him, "No, my parents are alive and I do work for the White Collar."

"She does Sherlock," Lestrade said looking at him, "I got a call from my superiors confirming her occupations and intent."

"I am never wrong," Sherlock stated, "You're lying."

"Hm," Olivia hummed raising an eyebrow at him before turning towards Lestrade, "If you make any advancements in the case, I need to be notified immediately."

Olivia nodded at the men before looking at Sherlock, "It's okay, you can be wrong once in a while. It was a cute trick, but that may only work for the dead. The living are much less, set in stone."

She sent him a smirk before walking out of the crime scene.

John looked over at Sherlock with his own raised eyebrow.

"She's lying," Sherlock stated turning back to the body, "Obviously."

Lestrade rolled his eyes.


	3. Chapter 3

**Author's Note:**

**Next chapter! Enjoy!**

* * *

3.

Back at 221b Baker Street, Sherlock Holmes was deep in his Mind Palace. But he was slightly agitated by his encounter by that woman. What was her name? Theresa something. Whoever she was she had forcibly broken into the sanctity of his mind. He was not wrong but she had smirked at his deductions and listed them away as a mere party trick.

"John," Sherlock said abruptly emerging from his Mind Palace, "I need a pen and paper."

Sherlock rolled his eyes at the shuffle he heard as he stopped to stare at the crime scene photographs. He had asked John this before, but of course he needed to tell Watson twice. His simple mind was sometimes slow to act. Not his fault, he was born without a noble mind such as his. However, he should not be subjected to this sloth and his idiot tendencies. John had lived with him for some time, Sherlock thought as John finally handed him the supplies he needed, he needed to get his act together.

"So," John started, "Now that you're out of your Mind Zone-"

"Palace," Sherlock said, irritated, "Mind Palace, John."

"Whatever," John shrugged, "Do you want to hear about the Mistress?"

"Yes," Sherlock mused, "I suppose if I find her she might be able to tell me who this Master is."

"Sherlock," John sighed, "The Mistress had stolen paintings at varying degrees of value from dozens of countries around the world. Not one of those governments was able to apprehend her."

"What is your point, John?" Sherlock scowled, "I am better than the government. Governments come to me for help."

"I will not lie, you have a brilliant mind, Sherlock," John said with a nod, "But this is a thief who stole the Mona Lisa and kept it for twenty four hours before breaking in and returning it to the LEAD detective's own house."

"But I don't want to apprehend her, I just want to talk with her," Sherlock said with a shrug.

John rubbed his face in exasperation, "Why would she come out with her identity for YOU, Sherlock?"

Sherlock stared at John, "Because why would I go to the police?"

"You would most likely get a handsome reward for brining in the Mistress," John said staring at his laptop, "She has stolen millions upon millions of pounds worth of paintings and jewels from multiple different countries: China, America, Spain, France and more. She's been at 'large' from the time before her theft of the Mona Lisa to now. That's more than six years and she has never been caught."

"John there are many criminals the government cannot put in prison," Sherlock stated, "She is not that extraordinary."

"On the contrary," a female voice lilted through the apartment, "She is quite extraordinary."

John looked up from his laptop abruptly seeing the slender blonde woman from earlier standing with her arms crossed at the threshold of their apartment. Sherlock turned slowly to face the woman.

"DI Lestrade said this is where you both lived," Olivia stated plainly, "I came to ask how you did receiving no leads on the victim's secretary and all."

John's eyes widened and he turned to stare at Sherlock who maintained his cool mask of indifference even after this woman had so blatantly insulted him.

"Yes the secretary has an alibi during the time of murder and I deduced other men she had sexual relation with so it is not a crime of passion, it is the work of a serial killer," Sherlock stated.

Olivia nodded with a slight smirk. It would never have been a crime of passion to start with. Other people have been killed by this Master so unless the secretary was absolutely insane, the Master was indeed a serial killer.

"I have a list of names for you to look into," Olivia stated.

"Oh really," Sherlock said looking un-amused

"Yes," Olivia said handing him Rollands' list of thieves he helped- minus her name, of course.

"What lead did you get on this?" John asked standing up from his seat on the couch walking over to look at the list of names Sherlock was now holding.

...

Olivia walked into an apartment building in the city, up two flights of stairs to an apartment door. She knocked twice waiting a moment before knocking three times rapidly.

She waited hearing the sound of socked feet on hardwood floor make way to the door. She stared into the peephole before the door opened revealing a six foot two leanly built man with a dimpled smile in place and twinkling blue eyes.

"Livy," he gushed, "So nice to see you again. How was Paris?"

"As clichéd as everyone makes it," Olivia answered with a tight smile, "But still very nice."

Anthony Thomas was nothing like his father. Marcus Thomas, jailed thief, was a surly man with a sleeve of tattoos on both arms but the man was quieter than a mouse. The complete opposite of Anthony. Tony Thomas was extremely attractive, extremely happy and as loud as stampeding elephants. But what Anthony lacked in stealth, he made up in intellect. He graduated high school at 12 and immediately enrolled in the University of Cambridge- the best university in the world before going to MIT and CalTech in America for a couple of years to get more training in different places.

And now he was a CEO in the best security system business in the world and Olivia's personal hacker and forger. Because like his father he had some criminal traits. Could be genetic, could be because of his intense loyalty to his father. Whichever it was Olivia was glad he remained in the business rather than going down some road of enlightenment and justice.

"You need a name and location for a job?" Anthony asked.

"No, I need a favor Tony," Olivia said smiling slightly.

"What kind?" Anthony asked brightening up immediately.

"I need your list," Olivia said walking towards him slowly blinking slightly.

"My top ten," Anthony re-stated, "Liv, you know I can't give you that. That's confidential information. I told you when you were chosen to be on it that I couldn't share who else was."

"Yes I understand," Olivia said stepping back and bowing her head.

She rolled her eyes so slightly at the floor Anthony would never see. She was playing him. Olivia needed this list. Her name was being scorned by some amateur, wannabe thief who decided to kill the art of thievery. The Master. Did this person want her to destroy him. Well congratulations Master, making it seem like she was associated with a no good murder was a great way to have that happen.

"It's just that someone is trying to make it seem like I'm associated with a murderer," Olivia said widening her eyes, "I can't let my reputation be ruined by this...amateur."

Anthony stared at her.

"Please Tony," Olivia said batting her eyes, "The victims were clients of your company, they had your security system. There is no signs of struggle in entering, it has to be one from the list."

"Or it could be some kind of tech genius," Anthony tried.

"Please Tony," Olivia said with an eye roll, "You developed the system. YOU are a tech genius. There is no way anyone would be able to one up you."

She was spreading the compliments thickly. It was disgusting, but it needed to be done.

"Okay," he said giving her a bright smile as he walked to his laptop.

Olivia let out a breath. She didn't like manipulating Anthony. She had known him since she was eighteen. He was one of the five people who knew about Olivia Tate. They were friends. She didn't want to manipulate her friends. But her reputation which she spent eight years crafting was in jeopardy. The other thieves, the petty ones and the world renowned knew of the Mistress and she wanted to stay true to her craft. Murder was cheating and cheating was below her.

She heard the sound of the printer behind her as Anthony walked towards it with a smile. He handed it to her and she gave him a small smile in return.

She scanned the list seeing names she knew and names she had only heard of. Men and woman alike, she would find them all. Question them all. She knew the police were looking for a man but she knew from experience, personal and from business, that the most cunning thieves were mainly women even if there were such a sparse amount of them.

"This is the top ten?" Olivia asked staring up at him.

"The top nine. The list is without your name of course," Anthony said, "Do you think one of these people is slandering your name? None of them will admit to murder."

"We'll see," Olivia said folding up the list and placing it in the inside pocket of her trench coat.

...

"The identity of my source is highly classified," Olivia answered looking John Watson in the eye.

"Why should we look into this?" Sherlock asked bluntly.

"Well your key suspect fell through," Olivia said raising a condescending eye brow at the cold man, "So it would be beneficial to through mine."

"And you cannot interrogate these people by yourself?" Sherlock asked, "Or do you feel that the validity of these names is questionable."

"Of course, not all of the people on this list are the Master," Olivia snapped, "I have not found the Master yet."

He was getting under her skin. She couldn't go interrogate these names because some knew her. And all knew her face. If one of them was indeed the Master, which she suspected one was, they wouldn't reveal anything to her. And as much as she hated to admit it, he did have a knack in reading people-deducing them was what Mycroft had said. She wouldn't have trusted the British police force to interrogate the people on the list.

Sherlock Holmes. He had this look about him that made her doubt everything she knew. made her think that it was impossible for one of these people in the top ten could be the Master. All are renowned thieves, minus two relatively new thieves that had somehow made it onto Anthony's list. That's what it is. That's what she was confident about. Those two names. They didn't hold the same amount of distinguish as the others did. They were more likely to besmirch the culture and art of thievery. The new generation, with their technology this and shortcuts that. A new thief, one not yet renowned, would be more likely to succumb to the cheatery that was murder in order to complete a heist. No integrity. She was right in trusting that the list would lead to the murder. No consulting detective, even the only one in the world could tell her otherwise.

"And you will not find the Master," Sherlock said bluntly.

"Well neither will you," Olivia told him putting her gloved hands on her hips.

"Of course I will, I have solved harder cases," he answered folding the list.

"I gave you the list, I found the names," Olivia said, "You needed me for more suspects and I need you to do that party trick you do on them to find out which one is the Master."

"It is not a mere party trick," Sherlock stated.

"Yes, I am aware," Olivia responded, "I have heard that it is quite extraordinary and I have read the good Dr. Watson's blog about it. But don't go around getting a big head, you still haven't 'deduced' me."

"I already have," Sherlock said, "Your biological parents are dead, you have been living alone and now that I have actually cared to listen to participate in a conversation with you I can tell by the timber of your accent that you travel much and do not stay in one location for long but you maintain the light Scottish brogue of the country you grew up in. You have a secretive nature and extremely quiet footsteps which is...interesting. I did not hear you come up the stairs into the apartment."

"And you have created a wall shielding you from emotions, you think them to be below you. Understandable of course, emotions interfere with practically everything. You were raised in a distinguished household, I can tell from your posture. You were extremely intelligent all your life, making you extremely annoying to the other kids. The way you interacted with that forensic man, Anderson, shows you weren't good at making friends and playing nice with others, so you were just as alone as I was before finding your blogger," Olivia countered.

"Amateur deductions, Watson could have done better," the younger of the Holmes brothers scoffed.

But Olivia could see the slight smirk of amusement and sparkle of shock that adorned the 'consulting' detective's face as well as the Look John gave the man.

"So we are in agreement," Olivia stated removing her hands from her hips.

The agreement being they would work together, acknowledging that both could figure out the identity of the Master on their own but would rather solve this case quicker. The faster they took to finish it, the faster they could go their separate ways.

"I believe we are," Sherlock answered.

"What just happened?" John asked looking between the blonde woman, Theresa, and his raven haired counterpart, confusion adorning his face obviously, "Have I missed something? What agreement?"

"Do try and keep up Watson," Sherlock said with an eye roll as he walked briskly out of the apartment.

John shot the woman one last look of confusion before following Sherlock out. As he turned his back, Olivia arranged her face into a look of extreme smugness. She would get this murdering thief soon.


	4. Chapter 4

**Author's Note:**

**Starting this up again...got inspired after getting Season 1 and 2 of Sherlock for Christmas.**

**Enjoy! Thanks for everyone that stuck with me on my break.**

* * *

4.

Olivia sipped tea from her cup daintily. She was sitting in a chair, the only one in the room staring into the cup, savoring the steam that drifted up from the heated liquid. She breathed in deeply. Nothing like a nice cup of tea after a murder.

Gosh that sounded morbid. Almost like a criminal. Olivia breathed out a slight laugh at her sarcastic thoughts.

Suddenly, a throat cleared breaking the woman from her reverie. Olivia set the cup down on the plate she was holding in her other hand before looking up slowly into the disapproving eyes of Mycroft Holmes. With that look, Olivia couldn't decide which brother Holmes she disliked the most.

"What did you call me here for, Mycroft?" Olivia asked with a slight scowl.

"I would like to know details about the Master case," Mycroft ordered twisting his fingers together.

"What?" Olivia asked mockingly, "The heart of the British government can't find out the details of such a case?"

Mycroft blew a sigh out of his nose, "My resources are being utilized in another area."

"Entirely?" Olivia questioned raising an eyebrow.

"My important ones," Mycroft said, "It is a very important cause."

"Hmmm," Olivia hummed pulling out her cell phone. She typed a quick message to her computer specializing resource.

-Trace all searches to the Mistress. Please.

OT-

She looked up at the eldest Holmes with a small smirk, "Well, your brother has proved helpful even though you informed me otherwise. He's questioning some thieves I believe to be a possible suspect for the Master."

"And these thieves," Mycroft started, "How are you sure of them?"

"Ah," Olivia smirked, "That's for me to know and for you to figure out."

Her cell phone dinged with a message.

-Looks like someone from the British government security team wants you...everything about you, what did you do Liv? They're getting close but don't worry I sent them a virus that will wipe out their entire hard drive and I bugged certain websites and files so it doesn't happen again. You owe me.

PM-

"And you'll never find out," Olivia said, narrowing her eyes and looking hard into Mycroft's.

After she said that Mycroft's cell phone dinged, his landline started to ring and the strange red (emergency?) phone beeped as well. Olivia's eyes and smirk widened. She crossed her legs and finally relaxed into the chair. She took another sip of tea as Mycroft answered the emergency phone first.

He listened carefully giving Olivia a reproachful glare to which she responded to with a raised eyebrow.

"What?" Mycroft said standing up, his chair sliding out from under him, "What do you mean we lost everything?"

Olivia smiled brightly and drank the rest of her tea. She set the plate down on his desk before placing the cup down with a soft click.

"Fix it," Mycroft ordered, he paused, "I don't care how you do it, just do it." He slammed the phone down and turned around running a hand across his face turning sharply to face the smug blonde.

"What did you do?" Mycroft raged slamming his palms onto his desk, "Do you have any idea what you have done?"

Olivia brightened considerably, "Oh Mycroft, Mycroft, Mycroft Holmes. For someone who thinks so highly of themselves, it was rather stupid of you to use government regulated computers to try and look me up."

The elder Holmes looked so enraged, "You will get the information back, immediately."

"No," Olivia said simply, "Why should I? You obviously do not understand our agreement."

"I wasn't aware we were in an agreement," Mycroft said scathingly.

"No," Olivia said again with a snicker, "But I informed you not to pry. I have information the government does not want leaked. I thought I made that clear when we chatted on the plane."

Olivia stood up staring up at Mycroft with a frigid glare, "How dare you not believe me? I don't think you understand what sort of information I have on your government. I have information on you as well, Mr. Holmes. But you disregarded that. Foolish man. You underestimate me. But you shouldn't, it just shows what an idiot you really are."

Olivia walked two paces, her heals clacking on the floor, "Mycroft Holmes, do remember that I stole the Mona Lisa one of the most heavily guarded artifacts in the world. I stole it at nineteen with one year of experience. Kept it for 24 hours before growing bored of it and putting it in the lead detective's apartment. Mr. Holmes, I do not think you know what you're up against."

Olivia took the steps and leaned in close to Mycroft's face. She reached into her trench coat's pocket and pulled out a removable drive.

"In case you didn't believe me, Mycroft Holmes," Olivia sneered passing it to the angered man.

He didn't reach for it, just stared at the blonde thief.

"I just want to show you my weaponry," Olivia stated plainly, "Just something to remind you of what happens when you try and play with me. And it will refresh you of the consequences of your foolish attempts. And to remind you of exactly who you are dealing with."

And with that Olivia spun around and walked out the door of his office putting her gloves on slowly.

Mycroft watched the Mistress exit the room before bowing his head to look at the drive. He sat down and plugged it into his computer. Images and texts and emails and files sprung up. He scrolled through the emails staring at each of the secrets the British government worked so hard at keeping. All the secrets that indeed could bring her to her knees.

He thought she had been exaggerating.

But she hadn't.

The last thing on the file of emails were three sentences.

"Don't try and destroy this I have others. Don't try and find the others I have plenty. Remember me, remember my power."

"Damn it," Mycroft swore banging his hand on the table. He unplugged the drive and pocketed it. Once this Master case was finished he would have Sherlock sniff out the others, no one could get the better of either of them and no one could beat both of them together.

Mycroft straightened up. That was a wonderful solution.

...

Olivia was sitting on the couch back at 221B Baker Street the humble living area of a not so humble man and his blogger. She was currently looking through John Watson's blog about Sherlock Holmes on the laptop she had brought with her from her small flat. She tugged on the heart shaped pendant on her locket- well the locket of her late mother, her biological one, not the old village woman. Olivia had found it when she was searching for her files for the answers of her past.

She found it, appraised it with the eye of a true thief for a lot of money. She had planned on pawning it but decided to have her technical resource PM-Phillip Matthews change it so when it is opened it resembled the tip of a removable drive. The information is stored in the heart, which was rather large. It was quite funny to her. When she told Mycroft Holmes that he was the heart of the British government and she held the heart in her hand, he probably thought she meant HIM, she held HIM in her hand.

But no she was being clever. The heart referred to her locket. The only other drive of information she had against the government. She teased him by making another copy, teased him by telling him there were others. But it was just for the British government. He had no idea what other things she had on the other governments she had robbed.

Oh her heart. It was her lifeline.

She quickly stuffed the heart down her front, covering the chain with her scarf, her shirt and her trench coat when she heard footsteps coming up the stairs. The owner of one of the two footsteps unlocked the door and Sherlock Holmes stormed through.

He stopped and looked at her, a look which she returned easily. She smirked slightly watching his light blue eyes move quickly, he was analyzing...deducing her.

"Well?" Olivia asked staring at the youngest Holmes. Dr. Watson entered in after and looked surprised to see her.

"Well what?" John asked looking between the two.

"It depends," Olivia asked, "I'm waiting for Mr. Holmes here to either deduce me or tell me what you concluded with the names."

Sherlock took a sniff, lightly, "You were visiting someone as well why we were away."

Olivia tilted her head, raising an eyebrow, "And who might that be?"

"My brother, Mycroft Holmes," Sherlock stated.

"Interesting," Olivia said with a smile, "I had no idea you had a brother."

"Of course you did," Sherlock sneered, "You reek of the tea he imports from China. Apparently it helps with his weight loss."

Olivia could have sung. She had noticed the special tea the moment he started preparing it so she had sent one of her resources to go to a Chinese restaurant that had the same tea that Mycroft was using. She needed an alibi and she had gotten one easily. The people who worked there were easily paid off and a credit card in her name was used. Done.

"No," Olivia said, she enjoyed using the word against the Holmes brothers, "I was at a restaurant meeting my boss to talk about the case. We went to a Chinese place, I was not hungry so I ordered tea."

Sherlock stared at her with a look of utmost loathing to which she returned with a smirk.

"Now that that is finished," Olivia said standing up and putting her laptop in its carrier, "What about the names?"

Sherlock frowned, "Two names seemed equally suspicious: Toby Nevens and Adam Kane."

"Ah," Olivia said, pacing slightly, "The young ones, I was correct."

"Both are obviously skilled thieves," Sherlock said with a shrug, "But are they killers. I don't think so."

"They have to be," Olivia said furrowing her eyebrows, "This doesn't make any sense, no one else could have done it, it had to be one of the people in those names. It couldn't be any one else."

"They aren't killers," Sherlock said with an eye roll, "Toby had a shifty look, he has a guilty conscience but somehow suppresses it in his thievery. Toby Nevens has been suspected of stealing an Egyptian relic in a museum in England then returning them back to its rightful country. That is how he suppresses it. He still thinks he's doing good. But nothing can be proven so he still works"

Olivia nodded, "I've never been on his case, but the Mistress must have done something to make Toby believe murdering Lester Herman and leaving behind that signature. But what?"

"Then there's Adam," Sherlock said sitting down where Olivia was, "I thought him to be a killer, he is indeed a killer, but not the one we're looking for. He's been in jail for a month for killing a security guard on one of his heists. Sloppy. He was drunk though that's not in the police reports. But it is obvious."

"So why is his name on the list?" Olivia asked to herself. Anthony hadn't changed his list to fit this newly jailed thief. Why? The thieves of the top ten knew they couldn't always use their resources all the time because that would lead suspicion. It was a last resource not the first one.

"Perhaps your informer is incorrect," Sherlock informed her with an eyebrow raised.

Olivia glared at her, "Toby Nevens, I need to question him."

"I already did," Sherlock said.

"Not correctly," Olivia sneered putting the strap of her laptop carrier over her shoulder and started to exit the building before pausing, "Do you want to see how you interrogate a thief?"

Sherlock paused and looked up at the blonde woman, "Very well."

Olivia smirked and exited the flat, not bothering to look back.


	5. Chapter 5

**Author's Note:**

**Lots of thanks and smiles and rainbows to the people who reviewed, favorited and followed!**

**Enjoy the next chapter!**

* * *

5.

Toby Nevens lived in a nice flat. It was small on the outside but it looked fancy. You could practically smell the money. This was a thief that was doing well for himself. He obviously used the money he gained from the other countries he stole from. It didn't help that his daddy was wealthy, Olivia thought sarcastically.

She didn't have old money, she had dirty money, blackmail money, and stolen money. A lot of that money but she just had a small flat, a few knick knacks and some nice clothes. Things she deserved. Things she bought from hard earned labor, back from uni and from the library she worked at. Her actual job.

But whatever, Olivia shrugged. She didn't plan on stopping any time soon. Thievery made her important. It made her matter.

Sherlock rung the buzzer for Toby's flat. An older man with white hair and deep lines in his face answered the door. The butler.

"Can I help you?" the butler asked raising an eyebrow.

"May I speak to Toby Nevens?" Sherlock asked.

"Mr. Nevens is not in at the moment," the butler said.

"Then we'll wait," Olivia said flashing her credentials as Theresa Montgomery from White Collar.

"Very well," the butler said ushering the three in.

Olivia's heels clicked on the hard wood floor as they entered the sitting area of Toby's flat. She took one of the fancily upholstered chairs quickly followed by John and Sherlock on the sofa.

Olivia watched the old butler turn to head back to whatever room he was originally in saying over his shoulder, "I'll inform Mr. Nevens of your presence and let you know when he returns."

"Thank you, we will wait here," Olivia said with a fake smile. The plastered grin fell from her face when the butler left. She stood up quickly taking off her heals one at a time so she wouldn't be heard as she walked around and inspected the room.

Toby Nevens was wealthy and his flat was much bigger on the inside than it was on the outside and much more garishly decorated. He was a bachelor but she was certain he or his mum had hired a decorator because the decor in his flat was not a reflection of a twenty some odd year old single man. It was more of a forty year old divorced woman with two cats.

Interesting.

She looked over at Sherlock Holmes's eyes flittering about the flat, most likely making the same conclusions and she did but at a much more specific detail. He probably knew if HE had hired or decorator or if his mother did.

"That butler is indeed informing Toby of our presence," Olivia muttered to herself as she examined a bust of some man-whose identity she didn't care to know, "But he is warning him to get an alibi and his story straight."

"How do you know that?" John asked, "He could just be informing him he had visitors."

"Nonsense," Sherlock said, "This butler is close to Toby. Been his butler since infancy you can tell by how he walks around the flat. New butlers are stiff but the older ones walk around like they own it. Also he had a pocket watch with either 20 or 24kt gold."

"24kt gold, the most expensive, pure gold out there," Olivia nodded moving from the bust to some of the china plates on display in a glass cabinet, "Not something your average butler would have, especially this one. One of his pants leg was hemmed once or twice, but it was an expensive brand."

"It was three times actually," Sherlock stated standing as well, "Also the sleeve on his coat pocket was frayed so he couldn't have an overly expensive watch when his suit was so old."

"He's only got a few suits or he's sentimental over his old ones, which is just strange," Olivia said with an eye roll, still fixated on a large, gold rimmed dinner plate bigger than two of her heads, "And the leather on his shoes is scuffed."

"What has the state of his attire got to do with his relationship with Toby or how long he's worked for him?"John questioned.

"Toby obviously purchased that for his butler, something a boss wouldn't normally do, so he must have been in the family for some time and trusts and respects Toby immensely," Sherlock informed him.

"Right, and Toby respects and trusts him, so he will definitely be preparing some kind of alibi to prove he wasn't the murderer, which we will be ready for," Olivia stated, "I'll have one of my resources look into it, once he tells us it."

Olivia put her heals back on and sat down on the chair satisfied with her inspection of the room. Toby was smart and craftly, well deserving of being in the top 10. But his one flaw was that he too used the security system that was linked with the thieving business, which was a flaw on his part. The fact he was new and made the list so quickly probably lulled him into a false sense of security. Never trust too much and always keep colleagues-especially amongst thieves-at an arm's length. Mistake number one Toby Nevens.

"When John and I questioned him," Sherlock began, "I noticed he kept shifting his eyes to the left wall over there at that painting every time I said thief which was twice. There's a safe there but we couldn't get to it."

"That's not all he noticed," John muttered with an eye roll.

Obviously Sherlock had reduced this man to a puddle.

"Do you know what was stolen from Lester Herman's flat?" Olivia asked randomly.

John flipped through a notebook quickly, "According to his wife, the thief took a sapphire necklace Lester had given her, a small painting-frame and all and a statue of a cat that had won at an auction. All worth more money than they appeared."

"Hm," Olivia hummed.

"Shouldn't you already know that?" Sherlock asked suspiciously. He was taking down the painting and sure enough there was a safe in the wall.

"Yes I already did, just making sure you were all at the top of your game," Olivia said cheekily.

Sherlock just stared at her before looking at the keypad, "He's smart, he used gloves when using this."

The consulting detective lifted a finger to enter in a guess at the pass code.

"I wouldn't do that if I were you," Olivia said.

"Well, I'm not you," Sherlock replied.

"That safe is programmed to sound an alarm if you entire an invalid code," Olivia drawled in her Scottish accent, "I would like to talk with the suspect before you get us kicked out of the flat."

Sherlock scowled and put the painting back on the wall.

Olivia took her phone out of her trench coat's pocket, fingering the warrant to search his flat (just in case- a last minute percaution) and sent a quick text to Anthony requesting the safe code for Toby's address. The safe was made by Rollands & Thomas, so Anthony should have it.

She pocketed the phone as they waited to confront Toby. Olivia would not have come to question five of the thieves in the top ten in person. Toby Nevens was a special case, one of the remaining thieves that had only heard of the Mistress, never been introduced. Only five thieves knew what she looked like, the rest of the renowned thieves of the world only knew her name.

Toby started two and a half years ago, she had been MIA two years ago and the yearly meeting happened before he became larger. So she could completely embody Theresa Montgomery and he'll be none the wiser.

Her phone dinged and she checked the password.

-13-18-77. Hope this helps. -A-

A birthday perhaps. If so, Toby was nine years older than her. But then again, you age in thievery was based upon your experience and success. The rest of the world should take note. She was scoffed at and deemed naive during college because she was the youngest when she was probably smarter than the lot of them.

Olivia and Sherlock's head perked up when they heard the door open and footsteps enter the house. Toby Nevens entered the sitting room soon after, thirty five years of age, dark curly hair and green eyes. She could see his shift eyed expression, his eyes going from her standing figure, to Sherlock and John's sitting ones.

"Nice seeing you two again," Toby Nevens said folding his hands behind his back, turning to look at Olivia, "How can I help you?"

"Theresa Montgomery," Olivia said flashing her credentials, "I'm here to ask you where you were last night between the hours of11pm to 2am."

"I told these guys I was at the pub down the street," Toby said looking confused.

"I'm here to tell you that your alibi didn't check out," Olivia said raising an eyebrow, "Where were you?"

"I don't have to tell you anything," Toby said narrowing his eyes.

"No, course not, don't speak at all," Olivia said with an eye roll, taking out the warrant and handing it to him, "But I'm going to take a look around your place."

Toby looked shocked and Olivia smirked. Took Mycroft Holmes two minutes to get that warrant signed. Very impressive being the heart of the British government and all.

Olivia took a slight bow before heading towards the painting. She looked back and was delighted to see him stiffen.

"Did you know that the most frequent place to hide a safe is behind a painting?" Olivia said with a small but then that turned to a disgusted look, "Also the most cliché."

She took the painting down and turned around, "Sherlock? Do you have a better idea of the pass code? Or do you want to tell us Mr. Nevens?"

Toby just stared at her and Sherlock stood up to walk to the safe.

"It's his birthday," Sherlock announced.

"Correct," Olivia said happily.

"How do you know?" Sherlock asked typing in the man's birthday. The safe door opened slightly with a hush of air.

"Looks like my resources ARE reliable," Olivia said with a smirk, opening the safe to reveal all of the stolen items, "Well, well, well, Toby Nevens are you aware that this cat, is a one of a kind sculpture belonging to a one dead man, Lester Herman?"

Toby sputtered, his eyes bulging in shock, "I don't know how that got there."

"Likely story," Olivia sneered, "Toby Nevens, you are under arrest for thievery and the murder of Lester Herman."


	6. Chapter 6

**Author's Note:**

**Thanks for sticking around since I haven't uploaded in a while!**

**Here's the next chapter!**

**Enjoy!**

* * *

6.

Toby Nevens, in handcuffs, was sitting behind a table as Olivia looked down at him. DI Lestrade was standing next to her on her left with Sherlock Holmes on her right. Sherlock stared down at the thief.

"He didn't want to kill Lester Herman," Sherlock said suddenly.

"What?" Olivia asked. The DI looked slightly confused as well. But only slightly. But then again Lestrade had worked with Sherlock longer than she had.

"Looking at him now, you can tell," Sherlock said, "What do you observe?"

"That he had all of Lester Herman's stolen knick knacks in his safe," Olivia stated blandly.

"No really look at him," Sherlock spouted moving his hands around frantically.

John Watson came into the room staring at his gesticulating form. He gave a sigh before looking at Olivia with a matter of fact expression, "Just do it, he'll act impressed then tell you all the things you did wrong. Just get it over with quickly."

Olivia gave a little smirk, "Fine," she turned to Mr. Nevens who had apparently been forgotten for a few moments there, "He's twitching, he's nervous, obviously, but the fact that he's TWITCHING is what's odd. Thieves have to be steady, no erratic limb movements or anything that could possibly disrupt a heist. So he's irrationally nervous."

She looked up at Sherlock who nodded quickly, urging her to continue, "Now that you have the obvious down, try really observing."

Olivia shot him a disgusted look, "Well why would he be irrationally nervous is the obvious question," her voice, at this point was dripping with sarcasm the idiot consulting detective missed, "Thieves are smooth, fearless, they break into houses and steal people's things without being caught for gods sakes, but he's here twitching like a Chihuahua."

"Again, the obvious, you are stating it," Sherlock drawled out, bored.

This Theresa Montgomery was nothing extraordinary, he could see that now. John Watson, no matter how prone to sentiment he might be, was one in a million. Possibly the only one that would be close to being tolerable to him.

"Oh, that's it," Olivia said pointing a finger in the air, "He's done this before, stolen-just stolen though and he's never acted like that. He's been followed by cameras his entire life, everyone would know if the son of a wealthy, important man, heir to said man's legacy was irrationally nervous. Perfect foundation for gossip. This is different. Why? It's a murder."

"You're still saying the obvious," Sherlock sighed with an eye roll.

Olivia huffed, "Stop interrupting me, you're making me lose my train of thought."

Sherlock smirked at her outburst.

"He hasn't murdered before, this is her first time, but the question is why? Why the sudden change?" Olivia asked walking around Toby Nevens, staring intently at the thief licking her lips, "You're a new thief-active four years at large two. You are still impressionable. Old thieves call thievery an art form, the point is to not kill the target's owner, but he did."

"And you said earlier that Toby had a guilty conscious, the only reason he can steal is because he feels he is justified," Olivia said. Her head shot up and looked at Sherlock, her eyes glowing with the excitement from her epiphany , "He wouldn't just kill on whim, so someone enabled him to do that, oh!"

"No one enabled me," Toby said, finally using his voice, "I did it myself."

Olivia scowled as she moved in front of him. She had enough of the cream puff. He shouldn't even call himself a thief, no respect for the craft whatsoever.

"No," Olivia said slamming her hands down on the table, "No someone enabled you. I know who you are Toby Nevens. The White Collar knows all about you," she added the White Collar as an afterthought, keeping up pretense and whatnot, "You're a no good thief. You think you're saving pieces but you're not. That one you stole from the New York museum in America? That was an offering given by the Egyptian government, you just dropping it off in a museum in Egypt was a sign that the American government didn't want their culture in their land. It was viewed as a sign of disrespect."

Toby Nevens looked stricken but Olivia plowed forward, "It took months of bartering and diplomatic dealings to prove that that wasn't a sign of disrespect. And that's all your fault."

Olivia stared at Toby intently watching his nervousness increase two fold. His hands shook violently as he put them on the table.

"Tell me who your enabler was," Olivia demanded, putting her face closer to his.

"The Master," Toby sneered at her faking confidence.

Olivia pushed off the table and looked at Toby with disgust, "Fine. He's your killer, put him in jail. Let him rot with the knowledge he almost ended an alliance between two countries because he thought he was doing the 'right thing'."

She started to walk out of the room, "I'm done here, I'll tell the White Collar what they want to here, but keep me updated on if he cracks in jail."

"You're a spineless, disgusting excuse of a thief," Olivia spit out at Toby Nevens, "I've met kleptomaniacs with more integrity than you. You don't deserve to be part of the ten."

Toby's head shot up as he stared at her, now he looked scared. He got the connection. Only the top ten knew of the top ten. When they used their connections, it was passed off as a faulty system and Anthony had his chance to put up another bogus 'new' security system. Her saying she knew made him realize she was a part of the top ten.

She gave him a small smirk before looking at a shocked detective inspector, a surprised Dr. Watson and a smirking Sherlock Holmes.

"It's been lovely working for you," Olivia drawled, "I hope to never be called to help with a homicide case again."

And with that she walked out of the room, the station, hailed a cab and go back to her small apartment.

...

Back at 221B Baker Street Sherlock Holmes was lying on his couch, his fingers placed under his chin accessing his Mind Palace. Theresa Montgomery was not who she said she was. She had denied his deductions obviously to keep her identity a secret.

But Sherlock could read through her mask like a book. She thought she was so clever. She was. She had almost fooled him in the beginning, with her credentials, her surprisingly good alias and knowledge of legal jargon. But he put the pieces back together.

Her footsteps-to silent. She always wore extremely high heels. Her steps were loud when she made them, but they were silent at any other time due to a long time of practice. Practice sneaking into places, stealing from expensive pieces even in a public setting.

Her hands never shook. She had said it herself, a thief always had steady hands.

She had examined the items in Toby Nevens's house with a critical eye as if appraising their value. She had known about the butler's watch-its wealth, value and amount of gold used to make it.

She didn't have many tells, not like other people. She WAS harder to read than most. Hard but not impossible. For some reason he couldn't read her entire life like he could with other people, other thieves he had deduced.

It was obvious to him, now, why he couldn't do so. She was The Mistress. She had years of hiding the things that gave her away. Though he looked hard enough, he saw the tells. The way her eyes flickered over a room, viewing the valuable goods in the room first, then the ones on the person. She walked soft when she didn't want to be noticed. Always referred to her position in the White Collar as an afterthought-yes he had noticed, John probably didn't, but Sherlock didn't wonder why, he was extremely normal brained. And the biggest tell that he could see through the mask was the fact she knew too much about thievery.

A normal person would assume it was due to her alliance with White Collar but Sherlock knew better. One-he knew she didn't work for White Collar. Two-the way she spoke, it praised thievery. She called it an art form. Someone working with White Collar would hate thieves, thievery due to being surrounded by numerous ones.

He got Lestrade to give him a file he had on the Mistress to see if he could have solved the case, had he been on it. But he couldn't. She was a good thief, detached from the target, leaving no evidence and always changing countries, Sherlock mused.

Sherlock emerged from his Mind Palace with a smirk. He knew of her identity, but he wouldn't say anything. She could be supremely useful in future cases, supremely useful.

His attention was drawn to a figure walking through the door. Mycroft.

John walked into the living room as well, "Mycroft," he sounded surprised, "What are you doing here?"

"Sherlock," Mycroft answered, "I hear your done with your case."

Sherlock gave him the barest of nods while picking up his violin.

"You worked with Theresa Montgomery," Mycroft continued, "Obviously you have figured out who she is."

"A thief?" Sherlock asked rhetorically, "Yes, I have. The Mistress I assume, due to her expert knowledge."

"Yes," Mycroft said, "She has been bothersome to the British government."

"Wait, Theresa is the Mistress?" John asked shaking his head, "What?"

"Yes John, try to keep up," Sherlock scoffed.

"Sorry, I couldn't identify a thief that no other government could," John said sarcastically.

"Well, the British government did," Mycroft said.

"Then arrest her," John said.

"They have no proof, John," Sherlock drawled, "Obviously."

"We can find proof," Mycroft spat, "It's just that she has information that the British government would rather not be leaked to the public."

"And what do you want me to do about it?" Sherlock asked.

"She has copies, I want you to find them," Mycroft stated, "All of them. I want her off the streets, off the world. I don't want her stealing anything else."

"Why should I?" Sherlock asked giving his brother a sarcastic smirk, "I rather enjoy having her get under your skin."

"Wow, that's the closest to admiration of another being as he'll get," John muttered going to the kitchen to make tea.

"No, you don't want to get it because you can't," Mycroft scowled.

Sherlock sat up, "Of course I can."

"No you can't," Mycroft said with an eye roll.

"Children please," John called from the kitchen, "No fighting."

Sherlock sneered at Mycroft before spitting out, "I don't want to help you put away the second person that can beat you. She could be quite valuable to me in the future. I thought you were the powerful British government."

"You don't understand, Sherlock," Mycroft said, concern actually leaking into his cold, Holmes tone, "She will ruin the British government. She has too much information on it, I've seen it. All theories, all have proof. She holds the heart of the British government in her hands as she has told me twice already."

Sherlock plucked his violin, ignoring his brother's sob story.

"So stop acting like a child and find it," Mycroft nearly shouted going back to his cold persona.

"No," Sherlock smirked.

"I will be back, I expect to come back with all drives found and ready to be handed to me for proper disposal," Mycroft ordered walking out of the flat.

Sherlock flickered his eyes to stare at his book case before rolling his eyes at his Mycroft's dramatics.

...

Olivia, back in her flat, was staring intently at her laptop, playing back the recording from the security camera she had installed quickly, placing it on a book in their apartment after Sherlock and John stormed out of the flat in excitement to question the thieves on her list.

She replayed Mycroft saying, "Obviously you know who she is" and Sherlock saying, "A thief, yes, The Mistress I assume due to her extensive knowledge."

Olivia glared at the pompous Mycroft Holmes. Even though Sherlock may have figured it out, something she didn't doubt, she had read Watson's blog. But it didn't matter whether Mycroft was telling someone that already knew. He didn't need to confirm his belief. The agreement was, don't tell anyone or the British government would fall.

This Master was her priority but Mycroft's folly had bumped him up to priority. It would take the Master a while to find someone that had connections like Toby Nevens. Or he would stop being a coward and start doing his own jobs. But she would focus on that later, didn't matter right now. She knew Sherlock would find her drive-he was a smart man, saw the world in a different view. The copies would send him on a wild goose chase, she was sure but he would eventually figure it out. And she couldn't have that.

Obviously, Mycroft didn't believe her. Olivia smirked, well, that would change. She watched the feed play through and noticed Sherlock's eyes flicker towards the bookcase, staring at a book, the book with her camera in particular.

Her smirk turned into a full blown grin of joy. Oh, this man was EVERYTHING she had thought he would be.


	7. Chapter 7

**Author's Note:**

**Next chapter!**

**Oh my god, thank you for all the fabulous reviews...I swear it was amazing, thank you so much!**

**Enjoy the next chapter, slightly shorter than the rest but I wanted to put it out there quicker than normal to show my thanks!**

* * *

7.

The next day, Mycroft Holmes was sitting in his office-which was in a complete disarray. His jacket was thrown over a lamp, his cuffs rolled up and his tie loosened, practically falling off his neck. The little hair he had on his head was in incredibly mused, like it had been run through by a stressed hand numerous times.

He had an empty bottle of scotch of scotch sat next to his equally empty glass next to his now folded hands. The usually neat and tidy man just sat in his chair staring at a blank wall. Multiple newspapers were strewn about the floor, all bearing the same headline: "GOVERNMENT SCANDAL COST TAX PAYERS MILLIONS". Outside his quiet office, the people were protesting, carrying handmade signs and marching across the street while police officers and government officials tried to quell the chaos.

He had a television brought into his office to get the second to second update on the madness that was brewing in the country-particular London.

A news reporter was speaking quickly in front of Buckingham palace. While the queen didn't have any power in the British government, she was the most important figurehead and standing in front of a palace made better scenery than a small office building. Also, it would draw more attention from press and tourists to protest outside of one of the biggest tourist destinations in the city.

"We are outside of Buckingham palace where people are coming in by the hundreds, demanding an answer to one question: What is the government doing to them?" the lady reported staring intently into the camera, "And Joe, I'd like to know what is going on as well."

Mycroft buried his face in his hands as his phones continued to ring none stop. Police stations, small sections of the government, larger sections of the government, other European countries they were all checking up on the government. Mycroft wished he could say this was the worst thing the government had ever kept from its people but it wasn't. There was worse. He had seen it, he had experienced it, he had helped hide it and he had met someone with proof to verify each one.

If the people were reacting this way to news that scored about a three on the scale of intensity and betrayal. England WOULD indeed fall to her knees. He made a mistake. He was foolish to doubt the Mistress.

She didn't seem like much. She wasn't very tall, she looked delicate, she lived alone and she worked as a librarian for cripes sake. She didn't look like a criminal mastermind. But that was idiotic mistake number one and in his unfortunate case, it was a huge mistake. He misjudged her, she probably knew it and he wasn't as guarded as he normally was. Completely stupid, he cursed himself, who in all that is holy underestimates a person who had stolen millions in paintings, jewels and sculptures.

His personal cell phone dinged with a new text message.

'Do you like what I have done?'

Mycroft narrowed his eyes yet looked at the phone warily.

'There's more where that came from.' the phone dinged again.

'Do you doubt me now Mycroft Holmes?' Mycroft scrambled to find the number of a tech expert the government had on hand.

'Stop what you're doing Mycroft' the phone read 'Don't bother'. He hesitated.

'I know what you're doing. You're going to phone Phillip Matthews. I wouldn't if I were you' Mycroft ignored this and continued to sift through his contacts.

'Tut, tut, haven't you caused enough damage' the incoming message read, attached to the text were photos.

It was two photos, one of the prime minister in bed with a blonde woman and another with the same woman's face taken from an extremely underground prostitution ring the British government had failed to stop completely.

'Take a look around and try me, Mycroft Holmes, try me' the next message read. Mycroft took a jagged breath. She knew too much. She had too much information. This was too much. He had underestimated her too severely and she took advantage of his nativity. The only person he knew could challenge him was his brother, she never met anyone who challenged him like this. Someone who had all the cards. She made him look like an idiot.

'Come out to play, Mycroft Holmes. -The Mistress'

...

Olivia smirked from the inside of her apartment watching her feed of Mycroft's office on her laptop. Oh the Holmes brothers were her new favorite play things. Well, Mycroft had it coming by not taking her threat to heart. That man was foolish. Honestly, the British government could do better.

She watched him panic in his office with a bright grin. Outside, she heard the faint sound of sirens. What a beautiful thing to wake up to. She had Phil release her story to the presses. It was only a slight theory, it was an anonymous email with the Prime Minister walking out of a motel. Then another with the prostitute, Jane, walking out of the same motel. With the same date in the time stamp for each picture.

Vague, but enough to start rumors and gossip. A little spice that the rag magazines could make into spicy curry of destruction.

The Mistress-1...The British Government-currently in the negative side of the number scale.

Olivia shut her laptop off completely, put it in her Longchamp bag before standing up to head to the library. She hailed a cab quickly-one of the ten things she would splurge on: transportation was one of the biggest.

She pushed open the heavy wooden doors to the library and was immediately greeted by Maria.

"Theresa, you're back, how was France?" Maria asked, her eyes bright from behind the information desk.

"Every cliché thing you've been told and better," Theresa gushed walking behind the desk and grinning. Maria was the closest thing she had to a friend in her twenty six years of life.

She called it on herself, though, having an alter ego-the Mistress-made her slightly nomadic, leading a solitary life. But she allowed herself to get close to Maria. She was young in high school, skipping a lot of grades. She was the youngest at uni and she opted out of having a dorm mate. She'd been alone her entire life, it was sad but she chose it. Actually, she probably chose her life because she was alone. Well. So she couldn't complain.

"How was the new girl holding up?" Olivia asked setting up her computer.

Maria groaned, "She is so annoying. Screws up check ins all the time. I was so happy to get rid of her."

Olivia chuckled, "So glad to know my presence was missed."

"More than missed," Maria said, "Irreplaceable."

"One of a kind," Olivia agreed.

Maria shot her a sarcastic grin before going to open the library doors, "Hey did you hear about the Prime Minister?"

"Yeah, on the telly," Olivia said, perking up, "Do you believe it?"

"No, the government just denied it," Maria said with a shrug, "The drama was nice while it lasted."

Olivia gave a fake laugh before biting her lip and starting to catalog new library card holders. Damn Mycroft, he fixed it, probably with bribery. Most likely paid off Jane the prostitute's pimp to doctor some photos of her with another man on the date in the time stamp.

Olivia shrugged. She gave him a scare, it was a small battle he had won, but she had the war in the bag, she thought fingering her necklace chain under her scarf.

...

Sherlock Holmes stood in front of his window playing his violin-Bach, powerful and loud. He wanted John annoyed and out of the apartment so he could think freely.

Mycroft had proved his belief that Theresa was the Mistress, rather obvious but it was nice to be proven right, that's why he never kept his deductions to himself. The look of shock they got when he told them every intimate detail of their life was refreshing because it meant he was right.

But this Theresa, he knew she was the Mistress but he didn't know anything else. No other intimate details-no tour de affairs, twice marriages at the same time, tragic family deaths besides her parents but he could tell that was a while ago or secret quirks that others hated. Which was strange. It was almost like she had no other life besides her secret thieving alter ego.

Sherlock stopped playing, put his violin down quickly and threw his coat on before running out of his flat.


End file.
